Below-Grade Applications

If the house is built on a slab, reconfiguring plumbing will involve additional challenges. In order to move or add new pipes, you may need to chip into the slab’s concrete.

Basement Bathrooms

Basement bathroom installations can also be challenging. If the basement is not pre-plumbed for a bathroom, considerable work will be needed to add the necessary water sources and drains. You can make the installation a little easier by locating the new bathroom next to existing plumbing, but adding the waste drain lines will be the most difficult. You will first need to locate the main sewer or septic line and determine its location below ground level.

Many sewer lines are actually quite deep, and with proper excavating you may be able to form the necessary 1/4 inch per foot (6 mm per 300 mm) of slope that is required for good drainage. The sewer line depth may be recorded at the local city or county public works department. The location of septic lines may be recorded on the plan for the lot. If the records are not available, you may need to talk with an excavator who is familiar with the area or dig a test hole to locate the line.

Once the sewer line is located, you will need to compare it to the exact level of the proposed toilet installation. A plumber, contractor, or excavator can help you make this comparison. If the sewer line level is sufficiently below the level of the toilet, you can simply install a 3-inch (75 mm) drain line from the toilet to the sewer.

Ejector Toilets

When the drain for the new bathroom installation ends up below the main sewer line for the house, you cannot take advantage of gravity to remove waste and water. In this case, a sewage ejector toilet is needed to pump waste up to the main sewer line.

A typical ejector toilet has a pedestal made of polyethylene, which acts as a base for mounting the toilet. This pedestal, which is 5 to 6 inches (125 to 150 mm) high, can sit directly on the floor or be re­cessed into the floor. Recessing the pedestal will place the toilet level with the floor. Inside the unit is a set of impellors and a sewage ejector pump, which processes the waste and pushes it up to the main sewer line (see Figure 2.11). Tubs, showers, and lavatories can also be drained into the toilet ejector tank.

Some models of ejector toilets are designed such that the pump, vent, and pipes are located a distance behind the toilet. This makes it possible to build a wall between the toilet and the equip­ment, which allows for a cleaner installation and makes the pipes and equipment much less ob­trusive. In some situations, a false or raised floor can be used to give space for plumbing lines if you have enough ceiling height to do so.